With constant development of technologies, users have an increasingly higher requirement on audio quality of an electronic device. A main method for improving the audio quality is to improve a bandwidth of audio. If the electronic device codes the audio in a conventional coding manner to increase the bandwidth of the audio, a bit rate of coded information of the audio greatly increases. Therefore, when the coded information of the audio is transmitted between two electronic devices, a relatively wide network transmission bandwidth is occupied. Therefore, an issue to be addressed is to code audio having a wider bandwidth while a bit rate of coded information of the audio remains unchanged or the bit rate slightly changes. For this issue, a proposed solution is to use a bandwidth extension technology. The bandwidth extension technology is divided into a time domain bandwidth extension technology and a frequency domain bandwidth extension technology. The present disclosure relates to the time domain bandwidth extension technology.
In the time domain bandwidth extension technology, a linear predictive parameter, such as a linear predictive coding (LPC) coefficient, a linear spectral pair (LSP) coefficient, an immittance spectral pair (ISP) coefficient, or a linear spectral frequency (LSF) coefficient, of each audio frame in audio is calculated generally by using a linear predictive algorithm. When coding transmission is performed on the audio, the audio is coded according to the linear predictive parameter of each audio frame in the audio. However, in a case in which a codec error precision requirement is relatively high, this coding manner causes discontinuity of a spectrum between audio frames.